System for, and method of, blocking the passage of emboli through a vessel

ABSTRACT

A self-expanding filter has a deployable resilient distal portion with properties of passing fluid (e.g. blood) in a vessel (e.g. an artery) and blocking the passage of emboli in the fluid. The self-expanding filter is disposed in the vessel, in the direction of fluid flow in the vessel, with its resilient proximal and distal ends at positions past a lesion in the vessel. The distal end of the self-expanding filter is then deployed against the vessel wall. An interventional device, such as an expandable member (e.g. balloon) and expandable stent are disposed in the vessel at the position of the lesion in the vessel. The expandable member is then dilated to expand the expandable stent against the vessel wall and open the vessel at the lesion position. Fluid (blood) flows through the deployed distal end of the self-expanding filter and emboli created during the procedure are trapped by the deployed distal end of the filter. The expandable member is then collapsed after all of the emboli have been trapped by the deployed distal end of the self-expanding filter. The resilient proximal end of the self-expanding filter is thereafter deployed against the vessel wall. This causes the emboli to be trapped between the vessel wall and the proximal and distal ends of the self-expanding filter. Alternatively, the expandable member may be deflated and withdrawn from the vessel after the proximal end of the filter has been deployed against the wall of the vessel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application of a parent application having U.S.Ser. No. 09/469,933 filed Dec. 21, 1999, now U.S. Pat. No. 6,443,971whose contents are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates to a system for, and a method of, treatingoccluded vessels (e.g. an artery) and capturing friable emboli which maybreak away from the lesion in the vessel during an interventionalprocedure. The system and method of the present invention are especiallyuseful when performing carotid interventional procedures in order toprevent embolic debris from entering and occluding downstream bloodvessels leading to the brain which, if blocked, may cause a stroke.However, the system and method of this invention can be adapted by aperson of ordinary skill in the art for use in numerous other vascularinterventional procedures.

In recent years, numerous procedures have been adapted for expandingblood vessels (e.g. arteries), at the positions of lesions in the bloodvessels, so that blood can flow through the blood vessels withoutobstruction from the lesions. In the process of expanding such bloodvessels at the positions of the lesions, emboli may become detached fromthe lesions and enter the bloodstream and subsequently migrate throughthe patient's vasculature to block blood vessels leading to sensitiveorgans such as the brain, where they may induce trauma.

Procedures have been adapted in recent years for preventing embolicdebris from flowing through the vessels in the direction of the bloodflow. For example, filters have been provided for trapping the emboli.When lesions develop in the carotid artery of a patient, the placementof a filter in the patient's vasculature can somewhat reduce themovement of the emboli to the patient's brain thereby preventing strokesfrom occurring.

Such filters are usually delivered in a collapsed position through thepatient's vasculature and are then expanded once in place to trap theemboli. After emboli have been trapped, the filter is collapsed toremove the filter (with the trapped emboli) from the vessel. However, itis possible for some of the trapped emboli to escape from the filterduring the time that the filter is being collapsed and/or removed fromthe blood vessel. When an interventional procedure is being performed ina carotid artery, even a trace release of emboli can be damaging. Forthese reasons, attempts to treat lesions in the carotid arteries havebeen somewhat limited due to the danger presented if all of the embolicdebris is not collected during the procedure.

Therefore, in light of the above, it would be desirable to have a systemand method which can be utilized to treat an occluded vessel and trapemboli that may be formed during the vascular procedure. Such a systemand method also must prevent the emboli from escaping from the filterduring the time that the vascular procedure is being performed.Additionally, it also would be advantageous if the filter could remainimplanted within the patient's vasculature, thereby eliminating apotential source for the release of trapped emboli since the filterwould not have to be collapsed and removed from the blood vessel. Such adevice or method should be easy to use and have minimal or no adverseimpact on the patient.

SUMMARY OF THE INVENTION

The present invention provides a self-expanding filter having adeployable resilient distal portion with properties of passing fluid(e.g. blood) in a vessel (e.g. an artery) while blocking the passage ofemboli released in the fluid. The self-expanding filter is to bedisposed within the vessel, in the direction of fluid flow in thevessel, with its resilient proximal and distal ends at positions pastthe lesion to be treated in the vessel. The distal end of theself-expanding filter is first deployed against the vessel wall, readyto trap any emboli which-may be released into the blood stream. Arestraining sheath previously has been placed over the self-expandingfilter to maintain the filter in a collapsed position. When the distalend of the filter is to be deployed within the vessel, the physicianmerely retracts the proximal end of the restraining sheath the properdistance to expose only the distal portion of the filter. Since thefilter is self-expanding, the distal end expands and contacts the wallof the vessel to form a seal which prevents emboli from escaping. Bloodis permitted to pass through the fine openings of the filter whileemboli of particular size are trapped by the filter.

An interventional medical device can be placed in the area of the lesionto treat the lesion and expand the vessel. For example, an expandablemember (e.g. dilatation balloon) and expandable stent can be positionedwithin the vessel at the site of the lesion. The expandable member isdilated to expand the stent against the vessel wall and to open thevessel at the lesion position. The expandable stent also deploys andholds this portion of the vessel open. Any embolic debris created duringthe interventional procedure will be captured and retained by theself-expanding filter distal to the interventional site and will beprevented from traveling to downstream vessels where possible blockagecan occur.

After the interventional procedure has been completed and all of theemboli have been trapped by the filter, the expandable member at thelesion site can then be deflated and withdrawn from the vessel. Theremaining portion of the self-expanding filter can thereafter be fullydeployed against the vessel wall. This deployment of the filter causesthe emboli to be trapped between the vessel wall and the self-expandingfilter. The physician fully deploys the remaining portion of theexpandable filter by retracting the proximal end of the restrainingsheath until the expandable filter is fully unsheathed.

Alternatively, the expandable member may be deflated and withdrawn fromthe vessel after the proximal end of the self-expanding filter has beendeployed against the wall of the vessel to trap the emboli.

The self-expanding filter may be made from a self-expanding stent havinga strut pattern which provides an adequate filtering media that cansafely and effectively trap emboli of a given size. Alternatively, theself-expanding filter may be made from a filtering material which trapsthe emboli, but permits blood flow there through. Expandable members,such as self-expanding cylindrical rings, could be placed along thelength of the filtering material to create a cylindrical shape filterwhich will be expandable and able to trap embolic debris. Since theself-expanding filter can be made from biocompatible material, thefilter may remain permanently implanted within the patient's vasculatureto prevent any trapped emboli from being released into the blood stream.

These and other advantages of the present invention will become moreapparent from the following detailed description of the invention, whentaken in conjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic elevational view, partially in section, of asystem including a catheter, an expandable member (e.g. a balloon)disposed in a vessel (e.g. an artery) at the position of a lesion in thevessel, an expanding stent disposed on the expandable member and aself-expandable filter disposed on a guide wire at a position past thelesion in the direction of the fluid flow in the vessel.

FIG. 2 is an enlarged fragmentary view, partially in section, of thesystem of FIG. 1 showing the distal end of the filter deployed againstthe vessel wall at a position past the lesion in the direction of fluidflow.

FIG. 3 is an enlarged fragmentary view, partially in section, of thesystem of FIGS. 1 and 2 showing the expandable member dilated and theexpandable stent expanded against the vessel wall at the position of thelesion.

FIG. 4 is an enlarged fragmentary elevational view, partially insection, of the system of FIGS. 1-3 showing the distal end of theself-expanding filter deployed against the vessel wall at the positiondistal to the lesion and schematically showing the movement of theemboli from the lesion to the deployed distal end of the filter.

FIG. 5 is a fragmentary elevational view, partially in section, of thesystem of in FIGS. 1-4 showing the self-expanding filter fully deployedto trap any emboli debris between the filter and the vessel wall.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of a system, generally indicated at 10, is shownin FIGS. 1-5 of the drawings. The system 10 includes a catheter 12 whichis constructed to extend through a vessel 14, such as a patient'sartery.

The system 10 is adapted to be disposed in the vessel 14 (e.g. artery)to pass the fluid (e.g. blood) in the vessel and to block emboli 18 inthe blood. The emboli 18 may be produced during the interventionalprocedure as a lesion 20 is being expanded to open up the vessel 14. Thetrapping of the emboli 18 from flowing through the vessel 14 preventsthe emboli from possibly occluding smaller diameter blood vesselslocated downstream from the treatment site, which, if the procedure isbeing performed in the carotid artery, can possibly cause the patient tosuffer a stroke.

An expandable member (e.g. balloon) 22 is disposed on the catheter 12and a stent 24 is suitably mounted on the expandable member. Theexpandable member 22 and the stent 24 may be constructed in a mannerwell known in the art. The expandable member 22 and the stent 24 may bedisposed at the position of the lesion 20 as shown schematically inFIGS. 1 and 2. When the expandable member 22 is thereafter dilated, itexpands the stent 22 against the vessel 14 to open up the vessel. Thisis shown schematically in FIG. 3. The opening in the vessel 14 ismaintained by the stent 24 even after the expandable member 22 isdeflated and is thereafter withdrawn in the vessel from the position ofthe lesion 20.

A self-expanding filter generally indicated at 28 is adapted to bedisposed in the vessel. The filter 28 has a resilient proximal portion30 and a resilient distal portion 32, each of which has properties ofpassing the fluid in the vessel 14 while blocking the emboli in thefluid. The filter 28 is disposed in the vessel 14 at a position distalto the lesion 20 in the direction of the fluid flow in the vessel. Aguide wire 26 may be used to deliver the filter 28 to the position pastthe lesion 20 in the direction of the fluid flow. The filter 28 isinitially constrained within a restraining sheath 34 (FIG. 1) so thatthe filter 28 can be easily inserted into the vessel to the positionpast the lesion 20 in the direction of the fluid flow.

The self-expanding filter 28 is placed on a filter holder 21 which, asis shown in FIGS. 1-5, is an elongated tubular member having a distalend and a proximal end (not shown) located outside of the patient. Therestraining sheath 34 likewise has a distal end 25 and a proximal end(not shown) located outside of the patient. This restraining sheath 34is slidable over the filter holder 21 in a coaxial arrangement so thatthe physician merely has to move the proximal ends of the filter holder21 and restraining sheath 34 in order to retract the distal end 25 ofthe restraining sheath the needed length to deploy the self-expandingfilter 28. Both the filter holder 21 and the restraining sheath 34 aremovable within a lumen 27 formed on the catheter 12. It should beappreciated that a simple mechanism could be attached to the proximalends of the filter holder 21 and restraining sheath 34 to maintain therestraining sheath 34 at the desired location relative to the filter 28during usage. Such a mechanism would prevent the sheath 34 fromaccidentally moving which could cause the entire filter 28 to deployprematurely. Additionally, the filter holder 21 may include a fitting 23located proximal to the filter 28 to provide a shoulder element whichallows the proximal end of the filter to abut against when therestraining sheath 34 is being retracted. Such a fitting helps toprevent the filter from moving back with the restraining sheath 34 as itis being retracted. This fitting may be a radiopaque marker which alsomay assist the physician in visualizing the location of the filter whendeploying the device in the patient's vasculature.

The filter 28 is initially moved in the vessel 14 to the position distalto the lesion 20 using over-the-wire-techniques. The filter holder 21includes an internal lumen 29 which receives the guide wire 26. Thisguide wire 26 is initially positioned in the vessel 14 with the filter28 being delivered to the area of treatment using over-the-wiretechniques. The distal portion 32 of the filter device is then deployedas shown in FIG. 2. The deployment of the resilient distal portion 32 ofthe filter 28 is provided by moving the restraining sheath 34 relativeto the filter holder 21. This is indicated by a hollow arrow 38 in FIG.2. When deployed in the vessel 24, the distal portion 32 engages thewall of the vessel and prevents emboli from flowing past the filter 28.However, fluid is able to flow through the distal portion 32 of thefilter 28.

The catheter 12 including expandable member 22 and the stent 24 can thenbe disposed in the vessel 14 at the position of the lesion 20 usingover-the-wire techniques. In this manner, the restraining sheath/filterholder can be used as a guide wire to position the catheter 12 inposition. The expandable member 22 can then be dilated. This causes thestent 24 to expand against the wall of the vessel 14 and expand thevessel 14 at the position of the lesion 20. This is shown schematicallyin FIG. 3. When the vessel 14 is expanded at the position of the lesion20, any emboli 18 produced, as shown in FIG. 3, are prevented frompassing through the vessel 14 by the deployment of the distal portion 32of the filter 28 against the wall of the vessel 14.

When all of the emboli 18 created as a result of the interventionalprocedure are captured by the distal portion 32 of the filter 28, theexpandable member 22 can be collapsed and removed from the vessel 14 bymoving the catheter 12 out of the vessel. The stent 24 remains in thevessel 14 at the position of the lesion 20 to maintain the vessel openat the position of the lesion.

After the expandable member 22 has been removed from the vessel 14, therestraining sheath 34 is again moved relative to the filter holder 21 todeploy the remaining portion of the filter 28 against the wall of thevessel 14. This is shown schematically in FIG. 5. The movement of therestraining sheath 34 relative to the filter 28 is indicated by a hollowarrow 40 in FIG. 5. The proximal portion 30 of the filter 28 also isconstructed to pass fluid and to block the passage of the emboli 18. Theemboli 18 are accordingly retained in a pocket 37 defined by the filter28 and the wall of the vessel 14.

The system 10 may be used in conjunction with current compatibledevices. For example, the system 10 may be used in conjunction withballoon dilatation catheters, stent delivery systems, ultrasonic andlaser angioplasty devices and atherectomy catheters, and other medicaldevices. The system 10 will preferably be used during vascularintervention, in particular, carotid artery angioplasty and stenting(i.e. pre-dilation, stenting, post-dilation), however, it can also beused in any procedures in which potential release of emboli debris posesa problem.

The self-expandable filter 28 shown in the embodiments of FIGS. 1-5 is astent device which has a strut pattern having sufficient porosity toallow blood to flow through the struts of the stent but having smallopenings to prevent emboli of a particular size from passingtherethrough. The self-expandable filter 28 could also be manufacturedutilizing a filtering material such as Gortex® manufactured by W. L.Gore & Associates, Inc., or nylon, porous PTFE, Dacron®, or similarmaterial. This filtering material would have a number of self-expandingcylindrical rings attached to it to form a compositecylindrically-shaped filter. The self-expanding cylindrical rings couldbe made from a material such as Nitinol or other self-expandingmaterials which will allow the rings to be initially collapsed to asmall profile onto the filter holder 21. The restraining sheath willmaintain each ring in the collapsed position. Once the restrainingsheath is removed, each collapsed ring will move into its fully expandedposition and contact the vessel wall. Other embodiments of aself-expandable filter 28 can also be made using other designs andtechniques. Additionally, other suitable means for delivering theself-expanding filter 28 to the area of treatment also can be utilizedin conjunction with the present invention.

The filter holder 21 can be made from a material such as cross-linkedHDPE or other similar materials. The restraining sheath 34 can be madefrom a material such as polyolifin. A material such as polyolifin can beused since it has sufficient strength to hold the compressed filter andhas relatively low frictional characteristics to minimize any frictionbetween the filter 28 and the sheath 34. Friction can be further reducedby applying a coat of lubricant, such as Dow 360 or Microglide®, to theinside surface of the restraining sheath 34 before the filter 28 isloaded onto the filter holder 21. Alternatively, the distal most portionof the restraining sheath 34 could be made from polyolefin, or similarmaterial, and the remaining portion of the sheath could be made from adifferent material to provide added strength to the sheath.

Although this invention has been disclosed and illustrated withreference to particular embodiments, the principles involved aresusceptible for use in numerous other embodiments which will be apparentto persons of ordinary skill in the art. The invention is, therefore, tobe limited only as indicated by the scope of the appended claims.

1. A method of expanding a lesion in a body vessel and passing a fluidin the vessel while blocking the passage of emboli in the fluid throughthe vessel, comprising the steps of: providing an expandable member;providing a filter having partially deployable and filly deployablepositions; delivering the expandable member in the vessel at theposition of the lesion and deploying the filter in the vessel at aposition past the lesion in the direction of the fluid flow; partiallydeploying the filter against the wall of the vessel, thereafterexpanding the expandable member against the lesion to expand the vesselat the position of the lesion; and fully deploying the filler againstthe wall of the vessel to pin emboli against the wall of the vessel. 2.The method as set forth in claim 1, wherein: the filter is constrainableand is deployable from its constrainable position and the filter isconstrained during the movement of the filter in the vessel to theposition past the lesion.
 3. The method as set forth in claim 2,wherein: the filter has resilient proximal and distal ends which areconstrainable from deployment against the wall of the vessel and whichare deployable to positions against the wall of the vessel when theconstraints on the proximal and distal ends are released; and aconstraint is provided on the resilient proximal and distal ends of thefilter to provide for an initial release of the constraint on theresilient distal end of the filter and a subsequent release of theconstraint on the resilient proximal end of the filter.
 4. The method asset forth in claim 3, wherein: the constraint on the resilient distalend of the filter is initially released to provide for a deployment ofthe resilient distal end of the filter against the wall of the vessel;and the constraint on the resilient proximal end of the filter isthereafter released to provide for a deployment of the resilientproximal end of the filter against the wall of the vessel.
 5. The methodas set forth in claim 1, wherein: the filter has deployable resilientproximal and distal ends; the resilient proximal and distal ends of thefilter arc constrainable to positions displaced from the wall of thefilter; the filter is disposed within a restraining sheath during themovement of the filter to the position past the lesion; and therestraining sheath is movable relative to the filter to initiallyrelease the constraint on the resilient distal end of the filter and tosubsequently release the constraint on the resilient proximal end of thefilter.
 6. A method for expanding a lesion in a body vessel and passingthe fluid in the vessel while blocking the passage of emboli in thefluid through the vessel, comprising the steps of: providing aninterventional device for performing an interventional procedure in thebody vessel; providing a filter having partially deployable and fullydeployable positions; delivering the interventional device in the vesselat the position of the lesion; deploying the filter into die vessel at aposition past the lesion in the direction of the fluid flow partiallydeploying the filter against the wail of the vessel; treating the lesionwith the interventional device; and fully deploying the filter againstthe wall of the vessel to trap any emboli between the filter and thewall of the vessel.
 7. The method of claim 6, wherein: theinterventional device comprises a self-expanding stent and a stentdelivery catheter.
 8. The method of claim 6, wherein: the interventionaldevice comprises a balloon-expandable stent and a stent deliverycatheter.
 9. A method for providing a system for expanding a vessel at alesion in the vessel, passing a fluid in the expanded vessel, andblocking the passage through the vessel of emboli in the fluid,comprising: providing an expandable member constructed for dispositionat the lesion in the vessel; disposing a stent on the expandable memberfor expansion against the vessel when the expandable member is expandedat the lesion; providing a self-expanding filter constructed fordisposition in the vessel distal to the lesion in the direction of thefluid flow; deploying the stein against the wall of the vessel to passthe fluid; partially deploying the filler to block the passage of embolireleased into the vessel; and fully deploying the filter against thewall of the vessel to create a trapping pocket with the wall of thevessel for retaining trapped emboli against the wall of the vessel. 10.A method for providing a system for blocking the passage of emboli influid flowing through a vessel, comprising: providing an elongatemember; providing a sheath slidably disposed on the elongate member;providing a self-expanding filter contained between the sheath and theelongate member; partially retracting the sheath; partially deployingthe self-expanding filter against the wall of the vessel to pass thefluid and to block the passage of emboli in the vessel; fully retractingthe sheath to release the self-expanding filter; and fully deploying theself-expanding filler against the wall of the vessel to trap the embolibetween the filter and the wall of the vessel.
 11. The method of claim10, wherein the elongate member further includes a shoulder locatedproximally to the filter, wherein the shoulder prevents proximalmovement of the filter when the sheath is retracted.
 12. The method ofclaim 10, wherein the self-expanding filter includes a resilientproximal portion and a resilient distal portion, and a filteringmaterial attached to the resilient proximal portion and to the resilientdistal portion, wherein the proximal portion does not contact the vesselwall when the self-expanding filter is partially deployed and the distalportion and the proximal portion contact the vessel wall when theself-expanding filter is fully deployed.
 13. The method of claim 10,wherein the self-expanding filler includes a filtering material and aplurality of self-expanding rings attached to the filtering material soas to form a generally cylindrical shape when the self-expanding filteris fully deployed.
 14. The method of claim 10, wherein theself-expanding filter includes a stent device having small openings toprevent the emboli from passing therethrough.
 15. The method of claim10, further comprising: providing a catheter having an expandable memberand a lumen; disposing a stent on the expandable member; anddimensioning the sheath and the elongate member so as to be movablethrough the lumen of the catheter.
 16. A method for providing a systemfor expanding a vessel at a lesion in the vessel and for blocking thepassage of emboli in the fluid flowing through the vessel, comprising:providing a catheter having an expandable member and a lumen; disposinga stern on the expandable member; providing an elongate member that isdimensioned to be movable through the lumen of the catheter; slidablydisposing a sheath on the elongate member; holding a filter between thesheath and the elongate member; partially retracting the sheath;partially deploying the filter against the wall of the vessel to passthe fluid and to block the passage of emboli in the vessel; fullyretracting the sheath to release the filter; and fully deploying thefilter against the wall of the vessel to trap the emboli between thefilter and the wall of the vessel.
 17. The method at claim 10, whereinthe elongate member further includes a shoulder located proximally tothe filter, wherein the shoulder prevents proximal movement of thefilter when the sheath is retracted.
 18. The method of claim 10, whereinthe filter includes a resilient proximal portion and a resilient distalportion, and a filtering material attached to the resilient proximalportion and to the resilient distal portion, wherein the proximal portion does not contact the proximal portion contact the vessel wall whenthe self-expanding filter is fully deployed.
 19. The method of claim 10,wherein the filter includes a filtering material and a plurality ofself-expanding rings attached to the filtering material so as to form agenerally cylindrical shape when the filter is fully deployed.
 20. Themethod of claim 16, wherein the self-expanding filter includes a stentdevice hiving small openings to prevent the emboli from passingtherethrough.